Syringes or medical syringes at their end as a rule comprise a Luer connection for the connection to a canulla or to a flexible tubing or likewise, which are to be connected. So-called Luer-lock connections are known, in order to secure this Luer connection, and these comprise an inner thread surrounding the Luer cone at a distance and screwed to the counter-connection. This on the one hand can be effected by way of rotation of the counter-connection, or however by way of rotating the thread, i.e. the threaded sleeve of the Luer-lock connection, for which the threaded sleeve is rotatably fastened on the Luer cone. The threaded sleeve however must be gripped on connecting, in order to rotate it. Thereby, there exists the danger that the fingers come into contact with the tip of the Luer cone itself, by which means regions which come into contact with the content of the syringe can become contaminated.